These investigations concern myocardial adaptation to stress in the rat. The stress initially used is that of pressure overloading of the left ventricle by banding of the the ascending aorta. Studies have been accomplished investigating the myocardial response to the pressure overloading in the moderately diabetic state. In the diabetic state there was cardiac atrophy, however, the degree of hypertrophy was similar to that in the non-diabetic animal. Studies are continuing by investigating this model in the severely diabetic animal. In addition, techniques are being perfected to measure protein synthesis rates of particular myocardial proteins in vivo by constant infusion of radioactive leucine in the rat.